Electroplating electrolytes



United States Patent 3,306,831 ELECTROPLATING ELECTROLYTES Richard P.Cope, Jr., Wilkinsburg, Pa., assignor, by mesne assignments, to CowlesChemical Company, Shaker Heights, Ohio, a corporation of Ohio NoDrawing. Filed Oct. 30, 1963, Ser. No. 319,982 18 Claims. (Cl. 204-43)This invention relates, in general, to novel electroplating brightenermaterials, electrolyte compositions and methods of electroplating. Moreparticularly, this invention relates to novel ester products which haveutility as additives to nickel, cobalt, nickel-cobalt and copper platingelectrolytes.

Bright nickel, cobalt and nickel-cobalt alloy coatings may be achievedby buffing dull electrodeposits to a high luster. However, certainorganic compounds may be added to standard plating baths to producebright deposits initially and eliminate the necessity for bufflng. Suchbaths are known as bright plating baths and the additives are known asbrighteners. The formulation of bright plating baths is complex and thecomplexity is compounded by further additions or formulations to makethe deposit ductile and to attain a leveling action in the bath in orderto cover surface imperfections, all in a wide current density range.

Addition agents are also employed in copper plating electrolytes forgrain refinement, brightness, leveling and to improve other propertiesof the copper deposit. Some addition agents contain sulfur and whilethey function effectively as brightening agents the code position ofsulfur tends to make the copper deposits brittle. Other additives areeffective grain refining agents at lower temperatures .but lose theireffectiveness at elevated. temperatures.

Accordingly, it is the general object of this invention to provide a newclass of materials which may be employed as additives in copper, nickel,cobalt and nickelcobalt alloy electroplating baths.

A more specific object of this invention is to provide electrolytes fromwhich bright, ductile and leveled nickel, cobalt and nickel-cobaltalloying coatings may be electrodeposited easily and consistently.

Another object of this invention is to provide methods forelectrodepositing bright, ductile and leveled coatings of nickel, cobaltand nickel-cobalt alloys.

Yet another object of this invention is to provide electrolytes andmethods for electrodepositing fine grained, lustrous and ductile coppercoatings over a wide plating bath temperature range.

It has now been discovered that a novel class of materials may .beprepared by the reaction of (A) a hydroxy or amine substituted aliphaticcarboxylic acid having from two to four carbon atoms with (B) at leastone acetylenic dibasic alcohol having not more than eight carbon atoms.The alcohols have the structural formula:

HO--CH X-CH OH in which X is selected from the group consisting of:

(1)CEC-, (2)ozCoH, (3)CECCEC (4)CHzCEC-CHz-, (5)0zo-om and(6)CH2GECCECCH;,-

Examples of suitable acids include glycine and B-alanine and lactic,a-hydroxy propionic, El-hydroxy propionic, a-hydroxy- -amino butyric,malic, glycolic, tartaric, ,B-hydroxy butyric and aspartic acids.

Acetylenic dibasic alcohols having not more than eight carbon atoms anda structure in which the hydroxyl ice groups are attached to theterminal carbon atoms and the acetylenic bond is not associated with theterminal carbon atoms may be employed. Examples of suitable alcoholsinclude butynediol, octadiynediol, 3-methylpentynediol-2,hexadiyne-2,4-diol-1,6, hexa-3-yne-1,6-diol and pentyne- 1,5-diol.

The reaction is conducted in an aromatic hydrocarbon liquid. The chargeof acid and alcohol is refluxed in a vessel equipped with a water trap.After the reaction is completed, i.e., when the theoretical water ofcondensation has been accumulated in the trap, the aromatic hydrocarbonin the reacted charge is removed by vacuum evaporation. The residue isdiluted with water and carbon treated to remove traces of the aromatichydrocarbon and other impurities. This reaction product, without furtherpurification, may be added to electroplating baths as a brighteningagent. It is believed that the reaction product is essentially orprimarily the ester of the described hydroxy and/or amino substitutedacids and the described acetylenic alcohols. It is also believed thatthese esters are eflicacious brighteners as described hereinbelow. Sidereactions apparently take place and, as noted, the reaction productitself may be employed to avoid the cost of purification.

The following examples will specifically illustrate the reaction productbrighteners, electrolytes and plating methods in accordance with thisinvention but should not be considered as limitations on the scope ofthe invention.

Example I About 0.1 mole of glycine and 0.1 mole of butynediol areintimately mixed and placed in a 500 ml. flask. The mixture is coveredwith 300 ml. of dry toluene. The flask is fitted with a water trap and areflux condenser." The reaction mixture is refluxed for 40 hours. Duringthis time, about 0.1 mole of water is collected in the water trap. Thetoluene is decanted from the brown residue in the flask. The residualtoluene is then removed by vacuum stripping. The residue in the flask isdispersed in water and filtered to remove the insoluble polymericmaterial. The resultant brown musty smellifig liquid is employed as anadditive to electroplating baths or electrolytes as outlined in theexamples hereinbelow.

Example II About 1 mole of threonine and 1 mole of octadiynediol arereactedin the manner outlined in Example I, hereinabove. The resultingtan solution is employed as an additive in the examples outlinedhereinbelow.

Example III Example IV About 1.5 mole of B-aminobutyric acid and 1 moleof butynediol are reacted in toluene until 1.3 mole of water iscollected in the water trap. The toluene is decanted and stripped fromthe solid by vacuum distillation. The

residue is dispersed in water. The solution is filtered and the filteredsolution is employed as an additive in the j examples below.

The resulting brown solid is dispersed in water,

3 Example V About 0.8 mole of B-aminopropionic acid and 1 mole ofbutynediol are reacted in xylene by refluxing the charge for about 60hours. In this time, about 0.85 mole of water is collected in the trap.The xylene is decanted. The residual xylene is vacuum stripped and theresidue is dispersed in water. The solution is filtered and the filteredsolution is employed as an additive in the examples below.

Example VI About 0.11 moles of butynediol and 0.1 mole of potassium acidtartrate are placed in the reaction vessel and covered withchlorobenzene. An azeotropic water trap is attached to the vessel tocollect the water formed by the esterification. The refluxing iscontinued until no further water is evolved. The chlorobenzene isdecanted and the reacted mass is dried at 100 C., under vacuum. Theresidual solid is dissolved in water and filtered. A light tan solutionresults and is employed as an additive to electroplating baths in theexamples hereinbelow.

The foregoing materials are incorporated into plating baths asillustrated by the following specific examples:

Example VII NiSO -6H O oz./gal 40.0 NiCl -6H O oz./gal 6.5 H BO z./gal5.0 Reaction product of glycine and butynediol, based on 100% solidsoz./gal 0.002 Temperature F 150 pH 3.4

A 3-ampere Hull Cell panel is plated for 5 minutes from this bath. Thenickel electrodeposit is hazy-bright, leveled and fairly ductile.

Example VIII NiSO -6H O oz./.gal 40.0 NiCl 6H O oz./gal 6.0 H BO oz./gal5.0 Reaction product of potassium acid tartrate and :butynediol, basedon 100% solids oz./gal 0.05 Temperature F 150 pH 3.8

A 3-ampere Hull Cell panel is plated from this bath. The panel is brightand leveled in the current density range of to 140 amps/sq. ft.Moreover, the electrodeposit was highly ductile.

Example IX NiCl -6H O oz./gal 30 H BO oz./gal 5.5 Disodium salt of2,5-benzenedisulfonic acid oz./gal 3.0 Sa-ccharin oz./gal 0.1

Reaction product of threonine and octadiynediol, based on 100% solidsoz./gal 0.0015 Temperature F.-- 150 pH 3.8

The deposit of nickel from this bath will be full-bright in the range of5 to 300 amp/sq. ft. The deposit will be ductile and have a fair degreeof leveling.

Example X CoSO 7H O oz./gal 65 NaCl oz./gal 2 H BO oz./gal 6 Reactionproduct of malic acid and octadiynediol, based on 100% solids oz./gal0.03 Temperature F. 140 pH 3.8

4 A leveled and fairly ductile deposit is obtained. The deposit will bebright in the current density range from 10 to 200 amps/sq. ft.

Example XI NiSO 6H O oz./gal 32 NiCl -6H O oz./gal 4 CoSO -7H O oz./gal0.4 H BO oz./gal 4 (NH SO oZ./gal 0.1 Sodium salt of2,7-naphthalenedisulfonic acid oz./gal 2.0 Reaction product of alanineand butynediol, based on solids oz./gal 0.2 Temperature F pH 3.8

The nickel-cobalt alloy ele-ctrodeposit on a B-arnpere Hull Cell panelis full-bright and leveled.

Example XII NiSO 6H O oz./gal 40.0 NiCl 6H O oz./gal 6.0 H BO oz./gal5.0 Trisodium-l,3,6-naphthalenetrisulfonic acid oz./gal 3.0 Saccharinoz./.gal 0.15 Reaction product of glycine and butynediol, based on 100%solids oz./gal 0.015 Temperature F pH 3.55

The deposit from this bath is mirror-bright and highly leveled over acurrent density range of 10 to 350 amps/sq. ft. Moreover, the deposit isductile.

The concentration of the described class of reaction products shouldrange from about 0.001 to 0.02 ounce per gallon when employed in nickel,cobalt or nickelcobalt alloy plating electrolytes. The foregoingconcentration range should be employed both with and without additionaladditives. Additional additives, known in the art and to be describedhereinafter may be employed to further improve other properties of thedeposit. A concentration below about 0.001 ounce per gallon will notproduce a significant improvement in brightness while concentrationsabove about 0.02 ounce per gallon, especially in the absence of otheradditives such as saccharin and the sodium styrene sulfonate to bedescribed hereinbelow, may produce deposits with evidence ofstress-cracking. The optimum concentration range is from about 0.004 to0.01 ounce per gallon.

It has also been discovered that sodium styrene sulfonate is effectivein brightening the deposits of nickel, cobalt and nickel-cobalt alloysfrom their respective electrolytes. A full-bright leveled but somewhatbrittle electrodeposit is produced in standard baths with no otheradditives. Other additives, as for example saccharin, may be employed incombination with the sodium styrene sulfonate to further improve theproperties of the deposit. Sacoharin, for example, will further improvethe leveling power of the bath.

The combination of sodium styrene sulfonate and the heretofore describedreaction product additives produce especially desirable and surprisinglyattractive electrodeposits of nickel, cobalt and nickel-cobalt alloys. Amirror-bright, ductile, leveled deposit with a surprising depth of colorwill be produced by electrolytes employing.

this combination of additives. The concentration of sodium styrenesulfonate, both with and without additional additives should range fromabout 0.005 to 1.0 ounce per gallon, the optimum range being from about0.01 to 0.75 ounce per gallon.

For example, nickel may be plated in accordance with the followingspecific illustrations.

asoassi Example XIII NiSO .6H O oz./gal 40.0 NiCl .6H O oz./ gal 6.5 HBO oz./gal 5.0 Saccharin oz./gal 0.134 Sodium styrene sulfonate oz./gal0. 5 Temperature F 150 pH 3.8

A 3-ampere Hull Cell panel is plated in this bath for five minutes. Afull-bright, leveled but somewhat brittle electrodeposit is produced.

Example XIV A 3-ampere Hull Cell panel is plated in this bath for fiveminutes. The panel is mirror-bright, highly leveled and ductile. Thebath has excellent throwing power.

I have also discovered that the reaction product of glycine andbutynediol is an effective grain refining agent in copper electrolytes.In copper plating baths, the concentration of the glycine-butynediolreaction product should range from about 0.002 to 0.07 ounce per gallonand preferably from about 0.004 to 0.05 ounce per gallon.

This additive is an effective grain refining agent at elevatedtemperatures, e.g. at 140 R, where some other additives lose theirefiicacy.

For example, copper may be plated in accordance with the followingspecific illustration.

Example XV 1 CuSO .5H O oz./gal 28.0 H 80 oz./gal 8.0 Dextrin oz./gal0.016 Reaction product of glycine and butynediol, based on 100% solidsoz./gal 0.016 Temperature F 140 A 3-ampere Hull Cell panel is platedfrom the above path. The panel is ductile, finely grained andsemi-bright. The bath has excellent throwing power.

While there have been shown and described what are presently consideredto be the preferred embodiments of the invention, modifications theretowill readily occur to those skilled in the art. the invention be limitedto the specific arrangements shown and described and it is intended tocover in the appended claims all such modifications as fall within thetrue spirit and scope of the invention.

I claim as my invention:

1. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and as brightener an effectiveamount of the prodnot of the reaction of (A) a substituted aliphaticcarboxylic acid having from 2 to 4 carbon atoms and at least onesubstituent selected from the group consisting of hydroxyl and aminogroups and (B) an acetylenic dibasic alcohol having not more than 8carbon atoms, not more than two triple bonds, and a structure in whichthe hydroxyl groups are attached to the terminal carbon atoms and theacetylenic bond is not associated with the terminal carbon atoms.

2. The acidic solution of claim 1 in which said brightener is present ina concentration of about 0.001 to 0.02 ounce per gallon of solution.

3. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt It is not desired,therefore, that and nickel-cobalt alloys containing a soluble salt ofsaid metal and as brightener an effective amount of the product of thereaction of (A) a substituted aliphatic carboxylic acid having from 2 to4 carbon atoms and at least one substituent selected from the groupconsisting of hydroxyl and amino groups and (B) an acetylenic dibasicalcohol containing not more than 8 carbon atoms and having the formula:

in which X is selected from the group consisting of (1)-CEC, (2)-CEC-OH-(3)-CECCEC, (4)CH2-CECCH2 (5)CEC-CHzand (6)CHzCECCECCHr 4. The acidicsolution of claim 3 in which said brightener is present in aconcentration of about 0.001 to 0.02 ounce per gallon of solution.

5. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and (1) as brightener aneifective amount of the product of the reaction of (A) a substitutedaliphatic carboxylic acid having from 2 to 4 carbon atoms and at leastone substituent selected from the group consisting of hydroxyl and aminogroups and (B) an acetylenic dibasic alcohol having not more than 8carbon atoms, not more than two tripple bonds, and a structure in whichthe hydroxyl groups are attached to the terminal carbon atoms and theacetylenic bond is not associated with the terminal carbon atoms and (2)sodium styrene sulfonate.

6. The acidic solution of claim 5 in which the brightener (1) is presentin a concentration of about 0.001 to 0.02 ounce per gallon of solutionand the sodium styrene sulfonate (2) is present in a concentration ofabout 0.005 to 1.0 ounce per gallon of solution.

7. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt, nickel-cobalt alloys andcopper containing a soluble salt of said metal and as brightener aneffective amount of the product of the reaction of (A) glycine and (B)butynediol.

8. An aqueous acid solution for electrodepositing copper containing asoluble salt of copper and from about 0.002 to 0.07 ounce per gallon ofsolution of the product of the reaction of (A) glycine and (B)butynediol.

9. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and from about 0.001 to 0.02ounce per gallon of solution of the product of the reaction of (A)glycine and (B) butynediol.

10. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and as brightener an effectiveamount of the product of the reaction of (A) potassium acid tartrate and(B) butynediol.

11. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and as brightener an effectiveamount of the product of the reaction of (A) threonine and (B)octadiynediol.

12. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and as brightener an effectiveanmount of the product of the reaction of (A) alanine and (B)butynediol.

13. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and as brightener an effectiveamount of the prod- 7 uct of the reaction of (A) malic acid and (B)octadiynediol.

14. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and (1) as brightener aneffective amount of the product of the reaction of (A) glycine and (B)butynediol and (2) sodium styrene sulfonate.

15. An aqueous acidic solution for electrodepositing a metal selectedfrom the group consisting of nickel, cobalt and nickel-cobalt alloyscontaining a soluble salt of said metal and (1) as brightener anelfective amount of the product of the reaction of (A) threonine and (B)octadiynediol and (2) sodium styrene sulfonate.

16. A method of electrodepositing a metal selected from the groupconsisting of nickel, cobalt and nickel-cobalt alloys comprising thesteps of electrolyzing an aqueous acidic electrolyte containing asoluble salt of said metal and (1) as brightener an effective amount ofthe product of the reaction of (A) a substituted aliphatic carboxylicacid having from 2 to 4 carbon atoms and at least one substituentselected from the group consisting of hydroxyl and amino groups and (B)an acetylenic dibasic alcohol having not more than 8 carbon atoms, notmore than two triple bonds, and a structure in which the hydroxyl groupsare attached to the terminal carbon atoms and the acetylenic bond is notassociated with the terminal carbon atoms and (2) sodium styrenesulfonate.

17. A method of electrodepositing a metal selected from the groupconsisting of nickel, cobalt and nickelcobalt alloys comprising thesteps of electrolyzing an aqueous acidic electrolyte containing asoluble salt of said metal and as brightener an efiective amount of theproduct of the reaction of (A) a substituted aliphatic carboxylic acidhaving from 2 to 4 carbon atoms and at least one substituent selectedfrom the group consisting of hydroxyl and amino groups and (B) anacetylenic dibasic alcohol having not more than 8 carbon atoms, not morethan two triple bonds, and a structure in which the hydroxyl groups areattached to the terminal carbon atoms and the acetylenic bond is notassociated with the terminal carbon atoms.

18. A method of electrodepositing copper comprising the steps ofelectrolyzing an aqueous acidic electrolyte containing a soluble coppersalt and as brightener an effective amount of the product of thereaction of (A) glycine and (B) butynediol.

References Cited by the Examiner UNITED STATES PATENTS 2,389,135 11/1945Brown 20449 2,389,179 11/1945 Brown 204-49 2,389,180 11/1945 Brown 204492,523,161 9/1950 Struyk et al. 20449 2,836,549 5/1958 No'bel et al.20449 2,870,069 1/1959 Ostrow et al. 20449 3,093,557 6/1963 Cope, Jr. etal. 20448 X FOREIGN PATENTS 1,017,873 10/1957 Germany.

JOHN H. MACK, Primary Examiner.

G. KAPLAN, Assistant Examiner.

1. AN AQUEOUS ACIDIC SOLUTION FOR ELECTRODEPOSITING A METAL SELECTEDFROM THE GROUP CONSISTING OF NICKEL, COBALT AND NICKEL-COBALT ALLOYSCONTAINING A SOLUBLE SALT OF SAID METAL AND AS BRIGHTENER AN EFFECTIVEAMOUNT OF THE PRODUCT OF THE REACTION OF (A) A SUBSTITUTED ALIPHATICCARBOXYLIC ACID HAVING FROM 2 TO 4 CARBON ATOMS AND AT LEAST ONESUBSTITUTENT SELECTED FROM THE GROUP CONSISTING OF HYDROXYL AND AMINOGROUPS AND (B) AN ACETYLENIC DIBASIC ALCOHOL HAVING NOT MORE THAN 8CARBON ATOMS, NOT MORE THAN TWO TRIPLE BONDS, AND A STRUCTURE IN WHICHTHE HYDROXYL GROUPS ARE ATTACHED TO THE TERMINAL CARBON ATOMS AND THEACETYLENIC BOND IS NOT ASSOCIATED WITH THE TERMINAL CARBON ATOMS.
 8. ANAQUEOUS ACID SOLUTION FOR ELECTRODEPOSITING COPPER CONTAINING A SOLUBLESALT OF COPPER AND FROM ABOUT 0.002 AND 0.07 ONCE PER GALLON OF SOLUTIONOF THE PRODUCT OF THE REACTION OF (A) GLYCINE AND (B) BUTYNEDIOL.